The invention relates to an adjustable vehicle seat with a horizontal seat adjustment and/or seat height adjustment and/or seat cushion depth adjustment as well as with a neck rest movable by an electric motor and guided by a sensor system which is influenced by the size of the user.
From DE 43 25 996 A1 an adjustment device is known for a motorized adjustable neck rest of a motor vehicle seat wherein the neck rest, which is fixed on guide rods and guided in guide sleeves, is coupled to a motor through an adjustment gearing. All of the parts of the adjustment device are thereby mounted in the upper region of a backrest body between the guide rods.
An adjustment of a neck rest of this kind is thereby carried out either by manually operating switches or by means of a memory function.
From DE 195 22 897 A1 an adjustable vehicle seat is known that has several motor driven adjustment devices where in dependence on the displacement of one adjustment device the remaining seat adjustment devices are moved by a control device automatically corresponding to memorized characteristics.
It is an often observed fact that little attention is paid to adjusting neck rests so that the risk of injury is considerably increased. The correct position of the neck rest is of crucial importance however, particularly in the event of rear-end collisions, and can prevent serious injuries.
On the other hand, the optimum position of the neck rest set in respect of safety requirements, can in certain situations be a hindrance, for example, during reversing, or when a backrest or seat is folded down in order to get in and out of the vehicle. In these cases a manual adjustment, or operation of a switch, has to be carried out.
An automatic adjustment of the adjustment elements of a vehicle seat, which also include those of the neck rest, through a memory function has been an expensive accessory item up until now. A memory seat of this kind stores the positions of the existing adjustment elements and starts them up when necessary. In this way it is possible to produce the optimum adjustment of the neck rest. Drawbacks with a seat of this kind however, are the relatively high weight as a result of the numerous adjustable adjustment elements, and high costs, so that this solution is only to be found in higher priced vehicle models. Furthermore, the positions that are to be memorized are set by a vehicle user so that errors can arise when adjusting the neck rest even when the positions are stored.
From DE 32 40 291 A 1 a device is known for adjusting the height of a neck rest which has an electric adjustment drive for adjusting the position of the neck rest. In order to move the neck rest into a position adapted to the seat user, a measuring device is mounted on the neck rest and interacts with a switch device. The measuring device determines the height of the seat user at a certain body point, such as for example a boundary line of the shoulders or head, as a value which is supplied to the adjustment drive in order to control the adjustment of the neck rest position.
Starting from the knowledge that the correct adjustment of the neck rest provides a critical safety function in a motor vehicle, the object of the present invention is to provide an economic vehicle seat that is independent of the level of equipment specification of the vehicle and in which the neck rest is moved automatically in dependence on sensed parameters which take into account the body size of the user.
Through an electronics unit that is related to the seat, vehicle seats which have not yet been fitted, or have only in part been fitted, with adjustable components can be equipped or fitted out with a neck rest adjustment without the vehicle having to already be provided with a corresponding pre-installed electronics unit.
Advantageously, an electronics unit is provided for controlling all of the seat adjustment devices that are to be controlled, i.e. the seat has no further electronics unit. The apparatus and assembly costs are reduced through the central control of the seat adjustment device.
In an advantageous development of the invention, the electronics unit is equipped for a maximum number of functions of the seat and the associated functions are activated after connection to the corresponding adjustment devices. According to this so-called plug and play principle, the electronics unit detects which adjustment devices are connected, for example, the electric horizontal seat adjustment, and then activates corresponding programs. If in the relevant vehicle equipment specification other variations of adjustment devices are proposed, for example an electric seat height adjustment, then a correspondingly different program is started.
It is favorable if the sensor system is a constituent part of a seat adjustment device that is adjustable by an electric motor, because information on the adjustment can be obtained directly in this way. It is also conceivable that the sensor system is a constituent part of a manually displaceable seat adjustment device. Thus, for example, the seat position is detected in an optical manner and transmitted to the electronics unit. Similarly, sensing is also possible through a rotary potentiometer on an adjustment device.
Advantageously, the neck rest is adjustable in dependence on several moving adjustment devices, because in this way a redundancy, or increased accuracy, is possible when setting the neck rest height in relation to the seat user. From a combination of two or more settings of the seat it is possible to obtain more accurate information on the optimum neck rest position.
In one variation of the invention, the electronics unit is programmed so that an adjustment of the neck rest is carried out in dependence on seat adjustment devices, and more particularly in dependence on the horizontal seat adjustment LV. Since as a rule there is a direct dependence between leg length and body length, it can be assumed that when the seat is positioned close to the steering wheel a lower neck rest height is to be set. Consequently, an adjustment of the neck rest into an upper position proceeds accordingly when the seat is set further away from the steering wheel. As an alternative, or in combination with the above, the seat height adjustment HV is provided as a controlling adjustment device and here, as a rule, the neck rest is extended further out the further the seat is moved downwards.
In another advantageous embodiment of the invention, the mirror adjustment SP and/or vertical adjustment of the seat belt point and/or adjustment of the steering wheel, or a sensor detecting the position of the head are provided as controlling adjustment devices.
In a further development of the invention, different adjustment speeds of the neck rest are recorded in the electronics unit. Thus, for example during a, by necessity, rapid displacement, such as when folding the seat or backrest forwards, the corresponding position can be achieved in a short time while an adaption to the horizontal seat adjustment LV or in the case of a manual adjustment can only happen slowly for reasons of positioning accuracy. Favorable in this connection is the option where a soft stop program is recorded in the electronics unit in order to avoid or reduce loud stopping or impact noises and in order to improve the wear of the adjustment device.
More advantageously, the electronics unit is coupled to a seat occupancy detection unit so that an adjustment only takes place on those seats which are actually occupied.
It has proved favorable if the electronics unit is constructed on the basis of power semiconductors.